The supply of at-home lateral flow Covid tests will be "constrained" in the coming weeks, the health secretary has said.
In a letter sent to MPs on Wednesday evening Sajid Javid said the public should continue to take tests when coming into contact with vulnerable people or doing risky activities.
But he admitted: “In light of the huge demand for LFDs seen over the last three weeks, we expect to need to constrain the system at certain points over the next two weeks to manage supply over the course of each day, with new tranches of supply released regularly throughout each day."
Mr Javid said MPs should instruct concerned constituents unable to find kits in the normal way to “see whether their local authority is distributing tests” or to check community facilities such as libraries.
“I would like to thank your constituents for their continued understanding and patience during this unprecedented time,” he said.
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The government has placed at-home rapid testing at the centre of its strategy to fight Covid, alongside vaccination – but their growing scarcity is causing problems.
People unable to find a test have to isolate for around 40 per cent longer under government rules, staying at home for 10 days instead of seven.
It comes amid concern about staff shortages across the economy, including in the NHS and on public transport – with Victoria Station in London already closed to its main operator due to a shortage of train crews.
Yet the NHS website has faced rolling shortages and pharmacists in high-demand areas have largely been out of stock.
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UK news in pictures 14 December 2021 The Royal Liver Buildings surrounded by early morning fog in Liverpool
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UK news in pictures 13 December 2021 People queue outside a walk-in Covid-19 vaccination centre at St Thomas's Hospital in Westminster
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UK news in pictures 12 December 2021 People take part in the Big Leeds Santa Dash in Roundhay Park, Leeds
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UK news in pictures 11 December 2021 People arrive at a Covid-19 vaccination centre at Elland Road in Leeds,
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UK news in pictures 4 December 2021 People walk through a Christmas market in Trafalgar Square
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UK news in pictures 30 November 2021 Workers put the finishing touches to the Trafalgar Square Christmas Tree ahead of the lighting ceremony later in the week
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UK news in pictures 29 November 2021 Home Secretary Priti Patel is greeted by a police dog at a special memorial service for Met Police Sergeant Matiu Ratana
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UK news in pictures 3 December 2021 An aerial picture shows a worker using a quad bike and trailer to transport freshly harvested trees at Pimms Christmas Tree farm in Matfield, southeast England
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UK news in pictures 3 December 2021 A pedestrian carries a dog as they dodge shoppers on Oxford Street in central London
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UK news in pictures 24 November 2021 Migrants are helped ashore from a RNLI (Royal National Lifeboat Institution) lifeboat at a beach in Dungeness, on the south-east coast of England, on November 24, 2021, after being rescued while crossing the English Channel.
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UK news in pictures 23 November 2021 The coffin of Sir David Amess is carried past politicians, including former Prime Ministers Sir John Major, David Cameron and Theresa May, Speaker of the House of Commons Sir Lindsay Hoyle, Home Secretary Priti Patel and Prime Minister Boris Johnson during the requiem mass for the MP at Westminster Cathedral, central London
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UK news in pictures 22 November 2021 The scene in Dragon Rise, Norton Fitzwarren, Somerset where police have launched a murder probe after two people were found dead
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UK news in pictures 20 November 2021 Police officers monitor as climate change activists sit down and block traffic during a protest action in solidarity with activists from the Insulate Britain group who received prison terms for blocking roads, on Lambeth Bridge in central London
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UK news in pictures 18 November 2021 The scene at a recycling centre in Stert, near Devizes in Wiltshire after a large blaze was brought under control. The fire broke out on Wednesday night the fire service has said and local residents were advised to keep windows and doors shut due to large amounts of smoke
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UK news in pictures 17 November 2021 The sun rises over South Shields Lighthouse, on the North East coast of England
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UK news in pictures 16 November 2021 ancer Maithili Vijayakumar at the launch of 2021 Diwali celebrations at St Andrew Square in Edinburgh
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UK news in pictures 15 November 2021 Forensic officers work outside Liverpool Women's Hospital, following a car blast, in Liverpool
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UK news in pictures 14 November 2021 Wreaths by the Cenotaph after the Remembrance Sunday service in Whitehall, London
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UK news in pictures 13 November 2021 Richard Ratcliffe, the husband of detainee Nazanin Zaghari-Ratcliffe, is ending his hunger strike in central London after almost three weeks. Ratcliffe has spent 21 days camped outside the Foreign, Commonwealth and Development Office in London without food. He began his demonstration on 24 October after his wife lost her latest appeal in Iran, saying his family was “caught in a dispute between two states”
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UK news in pictures 12 November 2021 Peter Green protesting outside the Cop26 gates during the official final day of the Cop26 summit in Glasgow.
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UK news in pictures 11 November 2021 Seagulls fly around the statue entitled 'Tommy', a first World War soldier by artist Ray Lonsdale at dawn in Seaham, Britain
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The government says it has taken steps to increase the supply of tests, with 300 million expected to be delivered in January, up from an original order of 100 million.
The UK government has so far declined to impose new Covid restrictions on people in England, putting it increasingly out of line with countries on the continent, as well as the other home nations.